Refractive variability using automated isentropic cross-section analysis

This report describes a computerized method for constructing vertical cross-sections of atmospheric refractivity and other properties, based on radiosonde measurements of temperature, humidity and pressure versus altitude. A sequence of individual radiosonde profiles provides information at separated locations in space or time. To facilitate recognition of trends and patterns in the refractive structure, and use of range-dependent propagation assessment models such as RPO (Hitney, 1992), additional data points must be determined at a higher lateral resolution than the profile spacing. An interpolative scheme has been developed, employing procedures intended to yield physically acceptable estimates of the intervening thermal and refractive conditions. Gridded fields of refractivity and other parameters are produced in an isentropic coordinate system which naturally preserves significant vertical details in the atmospheric structure indicated at the given profile locations. Examples of application to a VOCAR upper-air data set are given